Many bulk material products such as grains or other agricultural products contain pests, parasites, insects or other vermin, such as for example borers, lice, ticks, fleas or termites. It is convenient to fumigate such bulk materials in situ so that multiple handling in a further treatment process is not required and before the goods leave their geographic region of origin to prevent the spread of insects and vermin.
Fumigation devices for bulk materials are known in the art that involve placement of a heavy, impervious blanket or other covering article over the materials followed by subsequent addition of toxic gas flow under the blanket to fumigate the covered goods. In some applications a fumigation chamber can be developed using a flexible canopy or blanket supported by a frame structure. Current methods of fumigation under blankets are crude, ineffective at fully eliminating insect infestation since no mixing of gases with bulk materials can occur, and highly dangerous from an occupational health standpoint since the gases used for effective fumigation are extremely toxic. Subsequent atmospheric discharges of fumigant gases, for example methyl bromide, are highly undesirable also because this gas is an ozone depleting substance.